The present invention relates to the manufacturing of electrical cables and, more particularly, the automated assembly of electrical cables having at least one twisted pair of wires.
As used herein and in the claims, a xe2x80x9ccablexe2x80x9d is a length of insulated wire or wires, also referred to as conductors, terminated on at least one of its ends with an interface, also referred to as a termination, having a housing which allows access to the wire. Usually, a cable has terminations on both of its ends, but such terminations need not be of the same type. A cable is also referred to as a cord.
Electrical signal transmission cables for connecting pieces of equipment are of two forms: cables in flat flexible form having conductors always in the same position, or cables with twisted pair conductors.
A cable with unshielded twisted pairs (UTP) is terminated with a connector such as a 110 connector, a D8GS connector, an RJ45 connector or an RJ11 connector. RJ45 connectors and RJ11 connectors are sometimes used with modular cords. Selection of the type of connector for a cable is based on the performance levels needed for the intended use.
FIGS. 4 and 8 show two piece type 110 connector 200 and four piece type 110 connector 300, respectively. 110 connectors are used for patching between communication blocks for data and voice.
FIG. 20 shows D8GS connector 400. D8GS connectors are used for high speed data transmission.
FIG. 24 shows RJ45 connector 500. RJ45 connectors are used to connect voice and data communication equipment with RJ45 ports. An RJ11 connector is similar to an RJ45 connector except that the RJ11 connector is used with a single twisted pair while the RJ45 connector is used with four twisted pairs.
The size and shape of the housing of a D8GS, RJ45 and RJ11 connector is different than that of the housing of a 110 connector, and accordingly, the ordering of wires is different when assembled.
Each of the connectors in FIGS. 4, 8, 20 and 24 may be used with cable 100.
For clarity in the drawings, only reference numerals for the first and last of comparable elements are sometimes shown.
FIG. 1 shows cable 100 having four twisted wire pairs. Cable 100 includes jacket 111 and wires 120, 130, 140, 150, 160, 170, 180, 190 formed into a first twisted wire pair including wires 120 and 130, a second twisted wire pair including wires 140 and 150, a third twisted wire pair including wires 160 and 170, and a fourth twisted wire pair including wires 180 and 190. Each pair is twisted to reduce the cross-talk between the wires in the pair. The twist rate is different on each pair to further reduce cross-talk between pairs. The length of cable 100 ranges from a few feet to about 33 feet.
Jacket 111 is circular in cross section and is typically formed of flame retardant PVC or another plastic or insulative material. Jacket 111 functions as an outer cover to insulate the twisted wire pairs inside.
Insulating wire jackets 122, 132, 142, 152, 162, 172, 182, 192 are jackets for conductors 124, 134, 144, 154, 164, 174, 184, 194, respectively, and have respectively different colors for identification. Usually, jacket 122 is dark brown, jacket 132 is light brown, jacket 142 is dark blue, jacket 152 is light blue, jacket 162 is dark green, jacket 172 is light green, jacket 182 is orange and jacket 192 is white.
FIG. 2 shows an enlarged view of wire 120 in FIG. 1. Wires 125a-125g are combined together, typically having one central wire and the remaining wires wrapped around the central wire, and covered by insulating jacket 122 to form multi-conductor wire 120. The number of conductors inside a wire varies depending on the gauge. Generally, a plurality of thin conductors provides better conductivity with larger surface area than a single conductor, which improves transmission quality for high frequency signals. Also multi-conductor wires bend more easily and absorb mechanical load better than single conductor wires. Wires 130, 140, 150, 160, 170, 180, 190 have a similar structure to wire 120.
FIG. 3 shows cable 10 having two pairs of twisted wires. Cable 10 includes jacket 12 and wires 20, 30, 40, 50 formed into a first twisted wire pair including wires 20 and 30, and a second twisted wire pair including wires 40 and 50. Cable 10 is similar to cable 100 in FIG. 1 except for its number of twisted wire pairs.
FIG. 4 shows assembled two piece type 110 connector 200 which comprises first housing member 202, second housing member 204 and cable 100. Cable 100 and first housing member 202 are assembled first, then second housing member 204 is joined to first housing member 202 to form two piece type 110 connector 200. Members 202, 204 are shown in details in FIGS. 5 and 6, respectively.
FIG. 5 illustrates first housing member 202 of two piece type 110 connector 200. First housing member 202 has support members 206, 208, 210. Members 206 and 208 receive cable 100. Member 210 functions as a cable jacket stop when cable 100 is mounted on members 206, 208. Upstanding posts 216a-216g define gaps 220a-220h for each of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100. Insulation displacement contact (IDC) grooves 217a-217h receive IDCs 246a-246h of second housing member 204 of FIG. 6. Posts 218a-218g meet and separate each of IDCs 246a-246h of contacts 242a-242h of second housing member 204 of FIG. 6, so that it is easier for IDCs 246a-246h to cut insulation 122, 132, 142, 152, 162, 172, 182, 192 of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 when second housing member 204 is mated to first housing member 202. Latching arms 224a-224c and press fit members 212a-212b engage with corresponding shoulders and latching arms in second housing member 204 when the two housing members are mated. Openings 214a-214b around press fit members 212a-212b serve as complementary recesses to receive corresponding latching arms of second housing member 204. Gap spacers 222a-222d are located next to latching arms 224a-224c to maintain a space between first and second housing members 202, 204 when they are assembled.
FIG. 6 illustrates second housing member 204 of two piece type 110 connector 200. Second housing member 204 has cable receiving end 230 and upstanding projection 232. Projection 232 functions as a strain relief to overlying cable 100 when cable 100 is mounted thereon. Upstanding posts 238a-238h are provided to press wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 when two housing members 202, 204 are assembled together. Latching arms 234a-234d are provided for engaging with press fit members 212a-212b of first housing member 202. Between latching arms 234a-234d, openings 236a-236b are respectively provided to receive press fit members 212a-212b of first housing member 202. Openings 248a-248c are provided as respective shoulders for latching arms 224a-224c of first housing member 202. Slots 240a-240h are provided to receive the blades of contacts 242a-242h. IDCs 246a-246h are located at the end of contacts 242a-242h and cut insulation 122, 132, 142, 152, 162, 172, 182, 192 of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100, respectively, when assembled with first housing member 202.
A conventional assembling sequence of first housing member 202 with cable 100 will now be described.
An assembly worker prepares cable 100 by removing jacket 111 from an end of cable 100 to expose pairs 120-130, 140-150, 160-170, 180-190 of wires of cable 100. The assembly person appropriately relocates the pairs depending on the colors of the jackets, and positions cable 100 in first housing member 202. Jacket 111 of cable 100 seats in slots 206, 208 and ends just before slot 210. Starting from slot 210, the worker routes each of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 and respectively inserts them into gaps 220a-220h. After appropriate positioning, the assembly worker trims the ends of the wires using a suitable flush cutting tool to ensure that the remaining wire ends are uniformly positioned between upstanding posts 216a-216h and posts 218a-218g of first housing member 202. Next, the worker aligns and presses members 202 and 204 together, thereby inserting IDCs 246a-246h of contacts 242a-242g of second housing member 204. IDCs 246a-246h pierce insulation 122, 132, 142, 152, 162, 172, 182, 192 of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 when assembled with first housing member 202. The worker tries to maintain the twist rates between the twisted wire pairs, shown in FIG. 1, throughout the assembly process.
FIG. 7 shows first housing member 202 assembled with cable 100 according to the assembly method described above. As indicated in FIG. 7, the original twist rates on each of the twisted wire pairs 120-130, 140-150, 160-170, 180-190 is maintained as much as possible by the assembly worker during manual assembly. The end of wires 120, 130, 140, 150, 160, 170, 180, 190 are positioned and trimmed right after posts 218a-218g where IDCs 246a-246h of second housing member 204 cut insulation 122, 132, 142, 152, 162, 172, 182, 192 of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100.
FIGS. 8A-8F show the components of four piece type 110 connector 300 before assembly. Four piece type 110 connector 300 is designed to terminate a cable having four twisted pairs and to mate with a 110-type connecting block. Four piece type 110 connector 300 comprises base member 302, contact base 308, contact 309 (only the four top contacts are shown), first housing member 304 and second housing member 306. Base member 302 mounts cable 100 and is fitted between first housing member 304 and second housing member 306. Base member 302 has channels 317a-317h for receiving wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100. Channels 317a-317h of base member 302 provide routing paths for individual wires 120, 130, 140, 150, 160, 170, 180, 190, respectively. Base member 302 is also provided with IDC grooves 318a-318h to receive the IDCs of contact 309. Contact base 308 is assembled with contact 309, and then inserted into base member 302 in which cable 100 is mounted. First housing member 304, second housing member 306, contact base 308 and base member 302 are usually made from a non-conducting injection-molded plastic, such as polycarbonate, ABS, or PVC, while contacts 309 are made from a conducting material, such as stamped phosphor bronze plated with nickel and gold. Four piece type 110 connector 300 is designed to reduce the variation of cross talk throughout assembled connectors caused by lack of the control of routing of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 during an assembly process. Members 302, 304, 306, 308 are shown in detail in FIGS. 9, 10, 11 and 12, respectively.
FIG. 9 illustrates base member 302 of four piece type 110 connector 300. Base member 302 has slot 310 to receive cable 100. Slot 312 functions as a cable jacket stop when cable 100 is mounted in slot 310. Openings 314a, 314b form a through-space for latching arms and press fit members of first and second housing members 304, 306 when they are mated. Channels 317a-317h define routing paths for wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100. Upstanding posts 316a-316g are located along front edge 320 of base member 302 to define IDC grooves 318a-318h. 
FIG. 10 illustrates contact 309 placed on the top side of contact base 308. Contact base 308 also receives four bottom contacts (not shown) on its bottom side. The designs of the top and bottom contacts are identical. As configured for assembly, contact 309 is rotated 180 degrees about its longitudinal axis with respect to the bottom contact. IDCs 322a-322d of contact 309 and the corresponding IDCs of the bottom contact (not shown) cut and terminate insulation 122, 132, 142, 152, 162, 172, 182, 192 of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100. Grooves 328a-328d receive blades 324a-324d of contact 309. Openings 326a326d are provided for latching arms 338a-338d of first housing member 304, shown in FIG. 11.
FIG. 11 illustrates first housing member 304 of four piece type 110 connector 300. After base member 302 is assembled with contact base 308, first housing member 304 is attached to the bottom of the assembled members 302 and 308. First housing member 304 also opposes second housing member 306. Slot 330 is a receiving space for cable 100. Press fit members 332a-332b fit with latching arms 354a-354d of second housing member 306. Openings 334a-334b, 336a-336d serve as complementary recesses and shoulders for latching arms 354a-354b, 354c-354d, 358a-358d, respectively, of second housing member 306. Grooves 340a-340h fit with the vertically positioned blades of contacts 324a-324h of contact member 308. Upstanding protrusions 338a-338d press against the surface of the blades of contacts 324a-324h of contact member 308.
FIG. 12 illustrates second housing member 306 of four piece type 110 connector 300. Second housing member 306 is attached to the top of base member 302 after base member 302 is assembled with contact member 308 and first housing member 304. Cable receiving end 350 and upstanding projection 352 receive cable 100. Upstanding projection 352 functions as a strain relief to overlying cable 100. Latching arms 354a-354d and 358a-358d are provided for engaging with corresponding press fit members 332a-332b and openings 336a-336d of first housing member 304, respectively. Openings 356a-356b are provided to receive press fit members 332a-332b of first housing member 304. Grooves 364a-364h are provided to fit with one side of the vertically positioned blades 324a-324h of contacts 309. Upstanding protrusions 362a-362d are provided to press against the surface of blades 324a-324h of contact 309.
Assembly of four piece type 110 connector 300 with cable 100 is now described.
FIG. 13 is a view of base member 302 assembled with cable 100. An assembly worker prepares cable 100 by removing jacket 111 from an end of cable 100 to expose twisted pairs 120-130, 140-150, 160-170, 180-190 of cable 100. Jacket 111 of cable 100 is placed on slot 310 of base member 302 and ends at slot 312 of base member 302. Starting from slot 312 of base member 302, the worker routes each of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 and inserts them into the appropriate one of channels 317a-317h of base member 302. The assembly worker appropriately relocates the pairs depending on the colors of the jackets, and positions cable 100 in base member 302. The assembly worker tries to maintain the twist rates between twisted pairs 120-130, 140-150, 160-170, 180-190 of cable 100 throughout the assembly process.
FIG. 14 is a view of the sub-assembly of FIG. 13 after wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 have been positioned within IDC grooves 318a-318h of base member 302. The assembly worker guides wires 120, 130, 140, 150, 160, 170, 180, 190 through channels 317a-317h and bends the wires at front edge 320 of base member 302. Pyramidal structures at the top of upstanding posts 316a, 316c, 316e, 316g assist in the separation of individual wires 120, 130, 140, 150, 160, 170, 180, 190 from twisted pairs 120-130, 140-150, 160-170, 180-190 of cable 100 as the twisted pairs are inserted into IDC grooves 318a-318h. 
After appropriate positioning, the assembly worker trims the ends of wires 120, 130, 140, 150, 160, 170, 180, 190 using a suitable flush cutting tool. FIG. 15 is a view of the sub-assembly of FIG. 14 after wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 have been trimmed to terminate at the bottom of base member 302.
FIGS. 16A and 16B illustrate how contact base 308 loaded with contact 309 (not shown in FIG. 16A, see FIG. 10) is mated to base member 302 loaded with cable 100. After base member 302 is assembled with cable 100 and contact base 308 is assembled with contact 309, the assembly worker mates the assembly of contact 309 and contact base 308 to the assembly of base member 302 and cable 100. IDCs 322a-322h of contact 309 are received within IDC grooves 318a-318h of base member 302 at right angle to wires 120, 130, 140, 150, 160, 170, 180, 190, cutting insulating jackets 122, 132, 142, 152, 162, 172, 182, 192 of wires 120, 130, 140, 150, 160, 170, 180, 190, respectively.
FIGS. 17 and 18 illustrate how first housing member 304 and second housing member 306 are assembled onto the sub-assembly of FIG. 16. First housing member 304 and second housing member 306 are attached to the bottom and top of the sub-assembly of FIG. 16, respectively.
FIG. 19 is a view of the completed assembly of four piece type 110 connector 300. The worker needs to align and mate the latching arms, press fit members and openings of the connector housings repeatedly by hand. Alternatively, a manually operated press may be employed.
FIG. 20 shows a view of assembled D8GS connector 400. D8GS connector 400 comprises first housing member 402 and second housing member 404, and is used with cable 100. Members 402, 404 are shown in detail in FIGS. 21 and 22, respectively.
FIG. 21 is a detailed view of first housing member 402 of D8GS connector 400. Cord input aperture 410 receives and guides cable 100 and strain relief 412 receives and presses cable 100 when an assembly worker inserts cable 100 into first housing member 402 for assembly. Shoulder 414 is provided to block jacket 111 when cable 100 is inserted into first housing member 402. Gaps 419a-419h are provided to fix the wire ends when cable 100 is inserted into first housing member 402. Latching arms 416a,416b mate with openings 424a-424b of second housing member 404 as shown in FIG. 22. Lever 418 of FIG. 21 is provided to push lever 426 of second housing member 404 of FIG. 22 when D8GS connector 400 is unplugged from communication equipment (not shown).
FIG. 22 illustrates second housing member 404 of D8GS connector 400. Second housing member 404 is provided with cavity 420 to receive first housing member 402 which is assembled with cable 100. IDCs 422a-422h are provided to receive and cut insulation 122, 132, 142, 152, 162, 172, 182, 192 of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100, respectively. Openings 424a-424b are provided to receive latching arms 416a-416b of first housing member 402.
FIG. 23 is a view of first housing member 402 assembled with cable 100. An assembly worker removes jacket 111 of cable 100 from an end of cable 100 to expose the pairs of wires 120-130, 140-150, 160-170, 180-190 of cable 100. The worker inserts the exposed end portion of wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 through cord input aperture 410 of first housing member 402 until the leading end of jacket 111 abuts shoulder 414 formed internally in first housing member 402.
The worker then places the twisted pairs in grooves 419a-419h, respectively, of first housing member 402. The worker then trims the wire ends. The wire placement and trimming follows a generally similar sequence as shown in FIGS. 13-15. The worker then mates second housing member 404 to first housing member 402, as assembled with cable 100, by manually aligning IDCs 422a-422h of second housing member 404 with wire ends fixed at gaps 419a-419h of first housing member 402.
FIG. 24 shows a view of RJ45 connector 500, assembled with cable 100. RJ45 connector 500 comprises plug 502, management bars 508, 510 (not shown) and contact member 506. Management bars 508, 510 are provided to align wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 before the wires are inserted into plug 502. Plug 502 is provide with a cavity (not shown) to receive wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100. Strain relief 504 of plug 502 is provided to release tension exerted upon overlying cable 100. Metal contact 506 conducts signal from wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 to the communication equipment (not shown) when RJ45 connector 500 is mated to the plug of the communication equipment.
FIGS. 25A, 25B illustrate management bars 508, 510, respectively. Management bar 508 has grooves 509a-509d and holes 509c-509h. Management bar 510 has a similar structure to management bar 508. Each of the holes and grooves of management bars 508, 510 is used with a predefined colored wire jacket of cable 100.
The assembly process of RJ45 connector 500 is now described.
An assembly worker prepares cable 100 by removing jacket 111 from an end of cable 100 to expose the wire pairs 120-130, 140-150, 160-170, 180-190 of cable 100. The assembly worker orients cable 100 and sets wire pairs 120-130, 140-150, 160-170, 180-190 into a predetermined sequence depending on the color of insulating jackets 122, 132, 142, 152, 162, 172, 182, 192. The worker uses appropriate tools to spread jacket 111 of cable 100 so that wire pairs 120-130, 140-150, 160-170, 180-190 lay beside each other. The worker then untwists each of wire pairs 120-130, 140-150, 160-170, 180-190 and arranges the untwisted wires 120, 130, 140, 150, 160, 170, 180, 190 into two rows for ease of wire insertion into grooves 509a-509d and holes 509e-509h of management bar 508 and corresponding grooves and holes of management bar 510. The assembly worker inserts the arranged wires 120, 130, 140, 150, 160, 170, 180, 190 into the grooves and holes of the management bars 508, 510 according to a predetermined sequence. The assembly worker then trims any excess wire at the edge of outer management bar 510 and inserts wires 120, 130, 140, 150, 160, 170, 180, 190, as assembled with management bars 508, 510, into plug 502.
FIGS. 26A, 26B show wires 120, 130, 140, 150, 160, 170, 180, 190 of cable 100 assembled with management bars 508, 510 just before insertion into plug 502.
Due to the complex nature of the assembly process, it is typical for assembly workers to make mistakes throughout the assembly steps. The assembly workers create differences from cable to cable in untwisting twisted wire pairs, differences from cable to cable in how forcefully the wires are placed into slots of the connector housing, and errors in placing the correct color wires in slots of the connector housing. The assembly workers sometimes fail to bring the wires out to the edge of the connector housing.
While cables with flat flexible cables are known to be automatically assembled, twisted wire pair cables have always been assembled manually due to the complex nature of the assembly process discussed above. Nevertheless, automated assembly of twisted wire pair cables is desirable to reduce performance variations between cables.
In accordance with an aspect of this invention, there is provided a method of and an apparatus for automatically assembling a cable having at least two twisted wire pairs, each of the wires in the twisted wire pairs having a wire jacket with a respectively different color. The colors of the wire jackets are automatically detected and the twisted wire pairs are automatically positioned in a predetermined sequence based on the colors of the wire jackets.
A machine vision system is used to detect the colors of the wire jackets. A pin is utilized to automatically sequence the twisted wire pairs. Connector housings are automatically attached to the sequenced twisted wire pairs. The connector may be a 110 connector, a D8GS connector, an RJ45 connector, an RJ11 connector or other connector designed for automatic assembly.
In accordance with another aspect of this invention, there is provided a method of and an apparatus for assembling a cable having at least two twisted wire pairs, each of the wires in the twisted wire pairs having a wire jacket with a respectively different color. The colors of the wire jackets are automatically detected and the wires of the twisted wire pairs are automatically positioned in a predetermined sequence based on the colors of the wire jackets.
It is not intended that the invention be summarized here in its entirety. Rather, further features, aspects and advantages of the invention are set forth in or are apparent from the following description and drawings.